Grain Refinement via Inoculation

Inoculation means you add fine particles to the melt that act as artificial nucleation sites. This results in a finer grain, making the material tougher and harder. The particles also bind oxygen and thus prevent porosity. If you don't do this cleanly or keep the melt calm, the grain can become uneven. That leads to stresses and, in the worst case, cracks. So make sure you have good distribution and a calm, controlled melt, then it'll be fine.